The present invention pertains generally to folding furniture and, more specifically to tables having legs that fold compactly underneath the tabletop. In particular, the invention concerns a folding apparatus for extending-and retracting the legs.
Folding tables are widely used and derive their primary benefit from the relative ease with which they can be handled and stored when in the folded condition. One typical folding table leg is described in the patent to Weagle, U.S. Pat. No. 3,695,567. Folding tables of this type do not include a cross brace that provides fore and aft support for the table leg. An alternative design is a trestle-type table, such as the folding table shown in the patents to Burr, U.S. Pat. Nos. 3,818,844 and 4,444,124. In these tables, the vertical legs do not overlap each other; however, like the Weagle device, the folded legs themselves provide the stacking surface for other folded tables.
U.S. Pat. No. 4,838,180, owned by the assignee of this invention, describes a folding table that allows the table legs to be compactly folded underneath the tabletop, while still providing a uniform surface on which other tables may be stacked. One benefit of the folding table leg apparatus shown in the '180 patent is that the stacked tables are not supported on the folded legs, but rather on upright flanges forming part of the folding leg apparatus.
Certain details of the folding table leg apparatus of the '180 patent are depicted in FIG. 1. As shown in this figure, the folding leg apparatus 10 includes a top plate 11 that is mounted to the underside of a tabletop. The top plate 11 includes opposite side flanges 12 that project perpendicularly outward from the top plate 11. The side flanges provide a surface for stacking a folded table. The folding leg apparatus 10 of this prior device includes a tubular vertical leg 15 that terminates in a base or foot that is configured to support the table on the floor. A pair of support brackets 20 are each mounted to the top plate 11 at opposite sides of the vertical leg 15. The support brackets provide an attachment or pivot point for a pair of brace links 22. The brace links 22 are pivotably connected at one end to the support bracket 20 and at the other end to the vertical leg 15 by way of a lower pivot rod 24 that passes through the tubular leg. The vertical leg 15 is also supported by an upper pivot rod 26 that spans substantially across the width of the top plate 11 and is offset from the lower pivot rod along the length of the leg. The upper pivot rod 26 is pivotably connected to the side flanges 12 by way of opposite swivel brackets 28. Thus, the brace links 22 and swivel brackets 28 provide a mechanical linkage for controlled movement of the vertical leg 15 between its folded and its extended positions.
In a further aspect of this prior apparatus, a pair of release brackets 30 is provided for positively locking the upper pivot rod 26 in place when the vertical leg 15 is in its extended position. Each of the release brackets includes a lever arm 32 and an actuator plate 34 that is manually depressed to release the upper pivot rod. The actuator plates 34 are flared outward from the support brackets 20 so as not to interfere with the movement of the table leg 15 as it is pivoted between its folded and extended positions. A torsion spring 36 pivotably mounted on the outside of each support bracket 20 provides a positive torque to each lever arm 32 to keep it in its locked position when the release brackets 30 are engaged to the upper pivot rod 26. In this manner, the folding leg apparatus 10 of the '180 patent provides a positive locking mechanism to hold the vertical leg in its extended position. Likewise, the release brackets 30 provide an easy way to release the upper pivot rod so that the vertical leg can be rotated and pivoted to its stowed position. Greater detail concerning the folding leg apparatus 10 of this prior device can be found in the specification of the '180 patent, which description is incorporated herein by reference.
Details of another folding leg apparatus 40, shown in FIG. 2, are described in U.S. Pat. No. 5,913,272, the disclosure of which is incorporated herein by reference. In particular, the apparatus 40 includes a pair of opposite support brackets 42. Each of the support brackets 42 is defined by a mounting plate 41 and an integral mounting flange 50. Each of the mounting plates 41 includes a number of openings to receive a fastener for engaging the folding leg apparatus 40 to the underside of a tabletop.
The folding leg apparatus 40 includes a lifting handle 48 that is welded to each of the support brackets 42. The lifting handle 48 is provided for two purposes: first, to provide a hand hold to lift the table with the legs in their folded position; and second, to provide a surface for supporting the weight of another folded table stacked on top of the particular table to which the folding leg apparatus 40 is attached.
The folding leg apparatus 40 includes an upper pivot rod 56 that is secured to the table leg 45. In the '272 Patent, the table leg 45 is shown as including a pair of vertical bars that form each leg of the table. The upper pivot rod 56 is connected at its ends to opposite swivel brackets 58 by way of pivot screws. The connection between the upper pivot rod 56 and swivel bracket 58 is such that the rod can rotate relative to the bracket as the bracket itself is pivoted to extend or retract the table leg 45. The swivel bracket 58 is engaged to the upper pivot rod 56 at one end and is connected by way of a pivoting rivet at its opposite end to the mounting flanges 50 of the opposite support brackets 42. Thus, the swivel bracket 58 is permitted to pivot relative to the support bracket to manipulate the table leg. The swivel bracket 58 preferably includes a bend 58a adjacent the pivoting rivet so that the bracket can be connected to the upper pivot rod 68 outside the envelope of the support brackets 42.
The folding leg apparatus 40 also includes a lower pivot rod 54 that is engaged to the table leg 45 at a position offset along the length of the leg from the upper pivot rod. The lower pivot rod 54 is pivotably connected to the flange 50 of each support bracket 42 by way of a brace link 52. Specifically, the lower pivot rod 54 is attached to one end of each brace link 52 by way of a pivot screw so that the rod can rotate relative to the brace link. The brace link 52 itself is pivotably fixed to the mounting flanges 50 by way of a pivoting rivet, in a manner similar to the swivel bracket 58.
Each brace link 52 includes a pair of bends 52a and 52b, one bend being adjacent the rivet or mounting flange 50 and the other being adjacent the pivot screw or table leg 45. These bends are arranged to orient the connection to the lower pivot rod as close to the table leg 45 as possible. The narrow track of the brace links 52 and the wide track of the swivel brackets 58 help stabilize the table leg 45 when it is in its extended position.
The folding leg apparatus 40 of the '272 Patent includes a release lever 60 that is configured differently from the release brackets of the device in the '180 patent. The release lever includes an elongated actuator plate 64 that merges at its ends into lever arms 62. Each of the lever arms 62 defines a locking notch 63 that is formed to receive the upper pivot rod 56 therein. The release lever 60 is arranged so that the actuator plate 64 is disposed between the pivot point for the brace links 52 and the table leg 45. The release lever 60 is pivotably supported on the mounting flanges 50 of each of the support brackets 42 by way of a bolt 68. The bolt 68 is fastened to the release lever 60 by passage of the bolt 68 through the keyed openings in each of the lever arms 62, and is held in place by a nut.
The head of each bolt 68 also defines an enlarged spring slot that is configured to engage a portion of a torsion spring 66. In accordance with the invention, each bolt 68 extends through an opening in the mounting flanges 50 of each of the support brackets 42. The torsion spring 66 then passes over the head of the bolt so that an anchor arm of the torsion spring resides within the spring slot. The torsion spring 66 also includes a spring anchor 67 that is in the shape of a U to engage the upper edge of each of the mounting flanges 50. Thus, the spring 66 operates to provide torsional resistance against rotation of the bolt 68 relative to the mounting flange 50, which translates ultimately into torsional resistance against rotation of the release lever 60.
It can be noted that the actuator plate 64 is disposed within the envelope of the folding mechanism, and particularly between the support flanges 50. Thus, when it is desired to fold the table leg 40 to its stored position, the actuator plate 64 is depressed so that as the actuator plate 64 is pushed downward, the release lever 60 operates against the action of each torsion spring 66. As the release lever 60 continues to pivot about the axis of the pivot bolt 68 the locking notch 63 disengages from the upper pivot rod 56. The table leg 45 can then be moved to its stowed position by pushing the foot of the table leg toward the release lever 60. This action causes the free end of the table leg to swing outward thereby pivoting the swivel brackets 58 in a clockwise direction. Continued movement of the foot of the table leg 45 towards the release lever 60 causes the swivel brackets 58 to continue to pivot in a clockwise fashion, and to cause the brace links 52 to pivot in a clockwise direction. At this orientation, the table leg is generally parallel to the mounting plates 41 of the folding leg apparatus 40 and within the envelope defined by the lifting handles 58. Thus, additional tables can be stacked on the folding leg apparatus 60 without contacting the table legs themselves.
One benefit of the folding leg apparatus 40 described in the '272 Patent is that the release lever 60 is contained with the envelope of the apparatus 40 so that it is unlikely to be inadvertently contacted by a person sitting at the table. The release plates 34 of the apparatus 10 shown in the '610 Patent fall outside the support brackets 20 so they may be accidentally contacted and depressed by the foot of a person sitting at the table. However, one detriment common to the folding table leg apparatuses 10 and 40 is that the torsion springs, 36 and 66, respectively, are situated outside the support brackets and are therefore at risk of being contacted by a person at the table. This risk is mitigated somewhat in the apparatus 10 because the swivel brackets 28 are situated outboard of the torsion springs; however, the swivel brackets are then at risk of being contacted by the person.
There is a need for a folding table leg apparatus that incorporates the beneficial aspects of the apparatuses 10 and 40 disclosed in the '610 and '272 Patents, without the associated disadvantages. There is a further need for a folding table leg apparatus that is compact in size so that it can be used on differently sized tables and so that the overall envelope of the apparatus is minimal. There is an additional need for a folding table leg apparatus that can be easily released without the risk of the operator being pinched by the moving components of the apparatus.